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dgavin
2012-Dec-10, 09:29 PM
I cannot find the thread where we all posted about the 2004 swarm.

However some details form now 14 years of InSars measurements have been published.

The summary of it is that in 1996 a magma intrusion began just a few miles west of the three sisters. The intrusion increased in rate through 2003 to the point of 7cm a year uplift was indicated. Directly after the 2004 EQ swarm the magma intrusion decreased, as did the uplift to about 2CM a year, and has been decreasing slowly, to it's current rate of 5mm per year of uplift.

So two things learned here. The first is that the intrusion of magma at Three Sisters, while significantly slower, is still on going. The second is that this 2004 swarm, and the 2010 swarm of Yellowstone, both occurred at the time of a significant change (both decreases) in magmatic flow rates. This research may lead to new indicators of when magma flow rates change, and how to detect when these changes happen. It could lead to a potential early warning system of magma flow changes some decades down the road.

dgavin
2013-Apr-23, 08:24 PM
In as many weeks, a /possible/ third low frequency volcanic tremor, this time in the Sisters volcanic region, lasting over 40 minutes.

http://webfe2.ess.washington.edu/assets/seismograms/wife-bhz-cc/wife-bhz-cc--2013-04-22.png

This appears to be a clasic one, long duration, low frequency, and low magnitude, however no inndication from PNSN on location or depth, even though this showed up an multiple stations.

This is also part of normal background activity, but after posting about seismograph readings on BAUT since 2001, it's nice to see some not related to the St. Helens eruptions.

I posted the link above to the best of the webicorders for this event, as it really showed up nicely clean on that one, without interference from wind, regular quakes, chugging, or other effects.

dgavin
2013-Jul-02, 07:32 PM
Well this morning there were four quakes at the Three Sisters Uplift area, one of which appears to be a long duration slip lasting over a full two minutes, of which I'm clueless about. Also on the FRIS siesmographs, there appeared to be a very very faint signature of what I can only identify as rythymic chugging, that occured before and after the long duration slip, lasting around 5 hours all told.

dgavin
2013-Aug-30, 08:08 PM
There was what I can only call a low frequncy hiccup this week at the South Sister, lasting about 10 seconds coming in at 0 magnitude. This is not a signatue I've seen before, so far as I can tell it is not tectonic, volcanic, or hydrologic. This might be a naturally occuring, natural gas pocket venting.